Premium
Picomolar concentrations of tentoxin affect Mg 2+ ‐ and Ca 2+ ‐ATPase activities of plasma membrane vesicles from roots of winter wheat seedlings
Author(s) -
Klotz Martin G.,
Bérczi Alajos,
Erdei László,
Liebermann Bernd
Publication year - 1989
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1989.tb04646.x
Subject(s) - vanadate , vesicle , atpase , chemistry , biochemistry , stimulation , membrane , enzyme , biology , neuroscience
Purified plasmalemma vesicles were isolated in the presence of 250 m M sucrose from roots of 14‐day‐old seedlings of winter wheat ( Triticum aestivum L. Martonvásári‐8) by phase partitioning of salt‐washed microsomal fractions in a Dextran‐polyethylene glycol two‐phase system, and both Mg 2+ ‐ and Ca 2+ ‐ATPase activities were detected. Orthovanadate‐sensitive Mg 2+ ‐ATPase activity associated with the inside of right side‐out plasmalemma (PM) vesicles (latency 98%) was inhibited 76% by 0.3 m M Ca 2+ , Ca 2+ ‐dependent ATPase activity located partly on the inside and partly on the outside of plasmalemma vesicles (latency 47%) was not affected by Mg 2+ . Mg 2+ ‐ATPase activity was inhibited by 68% and inhibition of Mg 2+ activation by 0.3 m M Ca 2+ partly disappeared in the presence of 10 p M tentoxin, a fungal phytotoxin. Mg 2+ ‐ATPase activity remained inhibited up to 10 n M tentoxin while at 1 μ M tentoxin Mg 2+ activation was as high as without tentoxin. K + ‐stimulation and vanadate inhibition was increased and decreased, respectively, by 100 p M ‐10 n M tentoxin. Ca 2+ ‐dependent ATPase activity was continuously increased by 1 p M ‐10 n M tentoxin, but at 1 μ M tentoxin the stimulation disappeared. The effects of p M tentoxin on plasma‐lemma Mg 2+ ‐ATPase are discussed in relation to its influence on K + transport in wheat seedlings.